Damage can occur to fuel cell power plant components as a result of water freezing, whenever a fuel cell power plant is to be non-operational in an ambient environment in subfreezing temperatures. It is known to have an accumulator placed at the lowest point in the coolant system so that freezable coolant that actually flows through the fuel cell stack can drain toward the accumulator. It is also known to use external pumps to blow air or inert gas through various parts of the system in order to purge water therefrom.
However, use of an external pump increases the cost, size, weight and complexity of a fuel cell power plant and may be prohibitive in fuel cell power plants used to power electric vehicles. In addition, when the fuel cell power plant is shut down, an auxiliary power source, such as batteries or supercapacitors, must be utilized in order to power the purging pump equipment. This either reduces auxiliary power available for various functions, such as melting of ice or warming of the fuel cell stack, or else requires larger, heavier and more expensive auxiliary power sources, which also may be prohibitive in electric vehicles.